How To
Getting the Most From Your Laptop Battery
Some tips for extending the life of your laptop battery.
This lithium ion 11.1V - 6600mAh battery works with Dell’s Inspiron Series
September 24, 2008 by Ben Hardy

The battery plays a crucial role in a consumer’s overall laptop experience. Unfortunately, we usually don’t notice them until they start to fail on us. Understanding your laptop battery, knowing the different options available, and learning how to get the most out of yours can greatly improve user satisfaction. 

What’s Out There
Although lithium ion (LiON) rechargeable batteries are most common in today’s laptops, it wasn’t always the case. The first widely-used rechargeable was the nickel cadmium (NiCd). Useful in its day, inexpensive, and effective in a wide range of applications, the NiCd battery had a couple of drawbacks that needed improvement. One was the “memory effect,” (also known as “lazy battery”) where a battery that was recharged before being fully discharged would lose its full capacity, and instead “remember” the smaller capacity. The other drawback was the toxicity of nickel-cadmium (cadmium is a heavy metal). The next generation of laptop rechargeable batteries was the nickel metal hydride (NiMH), deemed a significant improvement over NiCd. For starters, NiMH batteries were non-toxic. They are considered more reliable, less expensive, and of higher capacity and output than NiCd batteries, and although they still suffer from the “memory effect,” it was less pronounced than their predecessor. 

The reigning king of the laptop battery is the lithium ion (also LiON or Li-Ion) battery. While more expensive than the previous two, LiON batteries do not suffer from any “memory effect,” are lighter than NiCd or NiMH batteries, and have a higher power density. The most current version of the LiON laptop battery contains a microprocessor that controls and monitors the charge and discharge rate, and feeds information to the laptop/user concerning remaining charge and estimated usage time. These advanced LiON batteries are commonly referred to as “Smart” batteries. 

If all laptop manufacturers are using lithium ion, why do battery capacities vary? To start, LiON batteries will differ in the number of cells included; the more cells, the greater the capacity. When purchasing a laptop from one of the bigger manufacturers (Dell, HP, IBM, etc.) the 6 cell LiON battery is most common. 8 or 9-cell varieties are often found as upgrades or purchasable as accessories, and will boast 20-30% capacity increase. Remember that each laptop differs, as well. Two different laptops using identical batteries may have very different runtimes. Usage time is subject to a great many variables, including processors, displays, and internal devices, to name just a few. Even if a manufacturer claims an 8-hour battery life (or 24-hours like HP), this will only be so under certain conditions. Think of it like the car industry’s Fuel Economy rating: the MPG figures are attained by running the car under ideal conditions, at a steady speed, on an inside treadmill. An actual driver uses the car much differently. Same deal with the laptop. 

When buying a replacement battery, be sure to match the voltage rating to the old battery. Batteries have three commonly advertised specs: voltage, amperes, and watt-hours. Watt-Hours (Wh) are found by multiplying the battery’s voltage and amp rating. Instead of amperes, manufacturers will often list milliamperes, and list the Milliamp-Hour (mAh) rating for the battery. For both Wh and mAh, a higher number means greater capacity. Keep in mind that batteries aren’t cheap. “My average cost for a decent 6-8 cell lithium ion battery is around $150,” says Anthony Cresegiona of BatteryMart, who also acknowledged that this was about one-third the price of a basic, stripped-down laptop. “Lithium isn’t cheap,” he continues, “but it’s a big improvement over NiCd and NiMH.”

Extending Battery Life
Lithium ion batteries do not require the same regular maintenance steps as the NiMH (e.g. routine full discharge/recharge to extend battery life), but there are a few commonly-accepted steps a user can take to get the most out of it. Before addressing those life-extending tips, consumers must first understand that a LiON battery loses capacity over time, and no amount of “cycling” (the process used with nickel-based batteries to restore full capacity) will return a LiON battery to its original state. Cell oxidation in a lithium ion battery is permanent, leads to charge loss, and cannot be halted. That said, getting the most out of each “cycle” or fully-charged battery can be done with the following steps:

Adjust Your Screen – If your computer’s power management options allow it, dim your screen to the lowest possible level. Set the screen for the lowest color setting (like 16-bit), as well. These two steps alone will do wonders. 

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Ben Hardy - Contributing Writer
Between watching re-runs of the The Jetsons and convincing his Insteon and Z-Wave controls to get along, Ben Hardy is immersed in the world of home automation, home control, and home networking.

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